This guideline by the Canadian Association of Diving Contractors (CADC) provides a basic understanding of the forces and hazards associated with Delta P.
The Canadian Association of Diving Contractors (CADC) recently published definitive guidance for divers working in differential pressure (Delta P) environments. Statistics from several occupational health and safety sources indicate that a high number of commercial diving accidents are linked to a lack of proper understanding of the hazards posed by differential pressures (Delta P) in various underwater work environments.
Differential pressure, known as "Delta P," can present unique and deadly hazards to divers. Differential pressures are created when two bodies of water intersect, each with a different water level, such as at a dam. The forces can be considerable when the water flows from a high pressure area to a low pressure area. A diver working on the high pressure side may be drawn into the flow and trapped. Serious injuries or death may occur.
Divers Institute of Technology (DIT) staff and members of a Canadian Standards Association (CSA) subgroup worked closely with CADC to develop the Guidelines. Divers Institute of Technology is incorporating the guidelines into its commercial diver training curriculum.
The guidelines are available here.